What is the maximum drawdown allowed when sampling?
What is the maximum drawdown allowed when sampling?
It depends on whether or not you have regulatory guidance documents that limit you to 3/10 of a foot or a 10th of a meter. For example, the latest EPA guidance document from Region 1 now recognizes that drawdown can exceed a 10th of a meter or 3/10 of a foot. The Vandenberg and Varljen study shows us that water level stabilization at any point is acceptable, but it is necessary to get the water level to stabilize. And the quicker it stabilizes, the better. Once you get that water level to stabilize, then you continue to pump and monitor indicative parameters until those parameters stabilize. In essence, the science doesn’t dictate a limit, but there may be regulatory limitations.
It depends on whether or not you have regulatory guidance documents that limit you to 3/10 of a foot or a 10th of a meter. For example, the latest EPA guidance document from Region 1 now recognizes that drawdown can exceed a 10th of a meter or 3/10 of a foot. The Vandenberg and Varljen study shows us that water level stabilization at any point is acceptable, but it is necessary to get the water level to stabilize. And the quicker it stabilizes, the better. Once you get that water level to stabilize, then you continue to pump and monitor indicative parameters until those parameters stabilize. In essence, the science doesn’t dictate a limit, but there may be regulatory limitations.